Doing it first for the 7 Plus increases the odds of success. 32 gig, 128 gig and 256 gig at 749, 849 and 949 but including at least 2 other differentiators (more internal ram and meaningfully more battery life on top of the greater battery life to date though I would suggest at least 1 more differentiator perhaps related to the camera) could be the secret sauce to making it all work out. You push more people towards the larger phone which is already more profitable and that compensates for the lost profits on the ram. The only way to pull this off with the 7 would be to include inexpensive differentiators and perhaps go down to two sizes, 32 and 128 like on the iPad Pro. Price them at 649 and 799 but include additional differentiators that push the higher priced phone. You'll drive enough traffic to the $799 to almost completely compensate.